Nuclear genes of Saccharomyces cerevisiae will be studied so as to contribute to our knowledge of eucaryotic gene organization and regulation. For these studies, the yeast ilv 1 structural gene will be utilized for genetic and physical analysis. The primary goals of this project are: 1. Genetic and physical analysis of an ilv 1 operator-promotor control region. 2. Analysis of ilv 1 gene organization - genetic and physical analysis of three domains which have been identified in the structural gene. 3. Isolation, DNA sequence and heteroduplex analysis of ilv 1 DNA containing various operator-promotor and domain mutations.